In the more advanced vehicles available today, such as buses, lorries, trucks, work vehicles, and cars, a network, such as a CAN network (Controller Area Network), is used to handle the communication between various units (ECUs, electrical control units) in the vehicle. It is possible that also networks of Ethernet type may be used in the future.
A CAN network is a network in which all nodes (transmitters and receivers) are connected to the same line. This means that when a node transmits a message, all elements of the network can read it. It means also that only one message can be transmitted at a time, since there is only a single line that can be used. The communication over a CAN takes place according to a specified CAN protocol.
Often, a number of CAN networks that are connected through a central control unit are arranged.
The ECUs that are connected to the CAN handle a large number of functions for the vehicle. These are, for example, functions related to change of gear, steering, engine control, braking, climate-control systems, lighting, driver comfort, alarms and safety.
According to the currently available systems, an ECU functions as a unit that controls its own system, such as the instrument cluster that monitors, among other things, the instrument panel. The ECU is connected through its transceiver to the CAN bus, and the transceiver can be considered to function as a link between the bus and the ECU. The transceiver has hardware to transmit and receive data from the CAN. Some ECUs are connected to several buses. When the ECU is switched off, it will normally avoid all energy consumption. As soon as an ECU receives a wake-up signal, while it is switched off, it will activate its energy transducer and provide power for itself, its transceiver and, where relevant, other components.
The units that are connected to the CAN can be activated or “awakened” in several different ways. It may be by messages over the CAN or over separate signal lines.
WO-2009/054769 describes a network configuration for vehicles for the connection of a number of control units via a network. The control units contain state components that influence the control units to undergo a transition to an active or passive state, depending on the state mode that is prevalent for the vehicle.
The concept of “operational states” is currently used to be able to define in a simple manner which ECUs are awake in a certain state, and what is allowed in a particular state. The operational state of vehicles today is normally based on the position of the key and the status of the battery. ECUs are awakened and kept awake in the various states with the aid of various signals from various signal lines, which are activated by the key mechanism.
It is not certain that a key will be used in the future. For this reason, it is desirable to define operational states that are based on other grounds, such as a certain button press, or whether the presence of a driver has been detected.
Through the infrastructure system according to the invention, the key unit will not be retained, and this means that ECUs on the network, such as the CAN bus, will be awakened and kept awake in another way.